Clamping device

ABSTRACT

A clamping device for fixing a tubular object (S), in particular for a seat post (S), comprises at least a clamping area ( 6, 7 ) which, under pressure, is elastically deformable and media feed lines ( 8, 9 ) to the clamping areas ( 6, 7 ). Set under pressure, the tubular object is fixed in a force-fit manner and without clearance. Used on a bicycle, e.g. the seat post (S) can be height-adjusted by means of a remote control (F) during a ride.

The invention concerns a clamping device for a releasable force-fitfixing of a tubular object composed of a sleeve comprising at least aclamping area which, under pressure, is elastically deformable. Suchdevices are necessary in techniques for different applications. Intelescopic tubes, for instance, sleeve and covering body must be fixedwith each other. In length-adjustable ski sticks a cone is strut forexample by means of a thread rod, which cone is thereby clamped in thecovering body. In parasol supports and similar a sleeve nut presses anannular clamping device against the sleeve. In mechanical engineering aclamping device is used to fix shafts with hubs.

From the DE-OS 43 30 634 is known a device for clamping an axiallymovable rod, wherein the rod is surrounded by a fourfold longitudinallyslotted sleeve. The sleeve is surrounded by an elastic shell to which isapplied a hydraulic pressure, whereby the tabs of the sleeve are pressedagainst the rod and are fixed to the said rod.

From the DE-OS 3000637 is known a releasable force-fit fixing of a shaftin a collar wherein the bore surface of the collar bears an intermediatering, which is composed of individual ring segments which can beadjusted hydraulically to the collar. Thereby, the individual ringsegments can, independently from another, be loaded via an adjustingelement each time by means of pressure means.

The DE 200 22 353 U1 exhibits a clamping sleeve for the construction oftools and devices which surrounds a columnar body and is surrounded onher part externally by a pressure chamber, during whose application theclamping sleeve clamps the body in a force-fit manner, whereby theoverall clamping sleeve is also deformed in the direction of thepressure chamber, and needs much place.

The known hydraulic clamping devices has the drawback that they areconstructively complex and can therefore not be realized particularlycompact and are relatively heavy.

It is therefore the objective of the invention to realize a clampingsleeve which avoids these drawbacks. A new clamping device was foundwhich can be used for a multitude of technical clamping connections.

The solution of this task consists in the fact, that the commonly fedmedia lines are provided for each clamping area of the sleeve, wherebyeach clamping area (6, 7) is formed by a recess at the external shell ofthe sleeve (2) and the external shell of the sleeve is pressure-tightcovered by a covering body (1). If the clamping areas are loaded bypressure, the rest of the sleeve is not deformed. The clamping areas arerealized in a manner that the rest of the material meets therequirements for an elastic deformability and stability.

The tubular object, which is fixed by the clamping device, can exhibititself each possible form. It can have a round cross section and can bea tube or a cylinder rod. The cross section can also be polygonal; itcould in particular exhibit the form of a regular polygon. Thereby theobject in the clamping device can be fixed somewhat radially. Accordingto this application the term “tubular” should comprise all tubularobjects with different cross sections, namely hollow objects or suchobjects of solid material.

The clamping device itself must be realized in a manner which is adaptedto fix the object by means of the elastically deformable clamping area,i.e., if the clamping area is pressed by means of an elastic deformationagainst the object, the clamping device must be realized in a mannerthat a counter bearing to the clamping area exists. Tubular bodiesaccording to the mentioned definition meet in general theserequirements.

When a multitude of clamping areas is axially and/or radiallydistributed disposed, the clamping effect is enforced and/orsymmetrised.

The media feed lines can be advantageously introduced in form ofchannels into the internal shell of the covering body and/or intoexternal shell of the sleeve, for example through milling. If it dependsless on the compact construction, for example also thin tubes can beinserted in the form of media feed lines into accordingly providedchannels.

The invention can be advantageously used for a hydraulic fixing of aseat post. Seat posts for fixing bicycle seats are usually fixed with amechanic gripper clamp in the seat tube Thereby the seat tube isgenerally slit at the upper end so that the circumference of the tubecan be reduced due to the clamping effect and that the seat tube isapplied force-fitted to the seat post. The gripper clamp is generallytorqued down with a nut or a quick-release-skewer is used, wherein theclamping force is attained in moving a lever. It is possible with such aquick-release-skewer is used to fix the saddle without a tool. This isfor example necessary when the bicycle shall be driven by persons withdifferent sizes or when the saddle height must be adapted to the sameperson due to certain conditions. The latter is for example the case forrides in difficult territories, as it occurs in particular duringmountain biking. Uphill the saddle height must be adjusted in anergonomically optimal manner, for attaining a good load transmission.During downhill run the driver must displace his centre of gravityrearward and downward according to the steepness and difficulty and mustfurthermore often displace his fundament behind the saddle. The deeperthe saddle the easer it is for the driver to displace actively anddynamically his centre of gravity, but looses therefore his lateralguiding forces, that he can obtain for an accordingly height adjustedsaddle with the internal sides of his shanks against the saddle. Theoptimal height of the saddle depends therefore on the correspondingdriving situation.

The drawback of the known clamping device consists of the fact, that thedriver must descend each time and adjust the height of the saddle. It istherefore desirable to realize a device for the height adjustment of abicycle saddle, which the driver can adjust during the trip. Suchsupports are provided on the market. In issue 11, 2006 of the magazineBIKE (Delius Klasing Verlag) is provided a test of so-called vario-seatposts. One of these two systems of the presented posts works with twooil chambers, which are interconnected via a valve. The opening of thevalve by means of the actuator, a tube can be moved up and down in theshaft. For attaining an upward force action, the lower oil chamber isfilled in addition with air. The so generated pressure pushes the postin drawing the actuator and a simultaneous discharge upwards.

This mechanism is on one hand complex and on the other hand the seatpost must have a certain clearance in the shaft for being able to adjustthe height of the seat post. The seat post is therefore—also if thevalve is closed—not fixed in an optimal manner. Furthermore the systemswhich are described in the test offer only a constructional restrictedseventy-five millimetre adjustment range.

According to this invention the sleeve is exactly surrounded in aperfect fitting by an external tube in the form of a covering bodyrespectively another sleeve. Both sleeves are interconnected in anadvantageous manner in welding, sticking, etc. of a certain zone, forexample at the upper and lower end, so that a medium, generally a fluid,introduced under pressure via the media feed lines, is not permitted toescape between the sleeves. This can be avoided by other means, forexample in arranging washers as for example o-rings etc.

Therefore an efficient height-adjustable seat post clamping can berealized by means of a clamping device according to the invention. Thetubular object to be fixed by means of the clamping area is, forexample, a seat post for a bicycle saddle. In this way a simple,effective and sure clamping of the seat post can be realized.

The hydraulic seat post clamping device cannot only be realized with theclamping device according to the invention, but can also be realized,for example, by means of the known, in particular hydraulic clamping. Itis furthermore possible to use other hydraulically actionable devicesfor clamping a seat post. Such devices are known in bicycles inhydraulically actionable brakes (MAGURA) and in disk brakes. They can beused in a corresponding construction for the proposed solution of aheight-adjustable seat post. This construction, which is less compactcompared to the device according to the invention, is not unfavourablein certain domains of mountain biking, for example in the so calleddownhill, because the robustness is more important than the reduction ofweight. The invention enriches the art only by the fact that theprinciple of hydraulic clamping is applied to height-adjustable seatposts.

In all seat post clamping devices according to the invention the seatpost can be loaded with a spring, which be for example a gas pressurespring, a spiral spring, or an elastomer. So it is possible to realizean especially remote height-adjustment of a seat post during the trip.

According to an embodiment of the invention the clamping device isrealized so that it can be integrated into the seat post of a bicycleframe or can even form a constructive unit with the said seat post. Itis possible in the first case to sell a seat post with the clampingdevice as an accessory. In the second case it is possible to save placeand weight because a portion of the seat tube can form simultaneouslythe covering body of the clamping device in integrating the media feedlines.

When the seat post be adjusted during the trip, it is advantageous toprovide means which avoid the rotation of seat post around thelongitudinal axis. This could be, for example, longitudinalconstruction, a tongue and groove construction or a polygonal internaland seat tube or similar.

A particularly advantageous embodiment of the clamping device is thatthe elastically deformable clamping area is the sleeve itself, wherebythe sleeve is composed in particular of plastics. When the sleeve itselfis sufficiently elastically deformable, no special clamping areas mustbe realized. A plastics sleeve has the advantage that it is relativelylight and shows good sliding possibilities. Any other material can beused which is correspondingly elastically deformable.

In the previous described embodiment the medium, for example a hydraulicmedium can be pressed directly between the covering body and the sleeve.An easier distribution and so an optimized pressure application isattained when at least one media feed line is provided which isintroduced in particular into the sleeve (21) in the form of acircumferential channel in the form of a spiral.

It is evident for the person skilled in the art, that the clampingdevice according to the invention can be realized also according to theprinciple of the cinematic inversion in a matter that the clamping areasact towards the exterior and fix a body surrounding the sleeve. Thesolution of such a task consists in a clamping device for a releasableforce-fit fixing of an object composed of a sleeve, which comprises atleast one clamping area which is elastically deformable under pressure,whereby simultaneously fed media lines are provided for each clampingarea, and whereby each clamping area is realized by a recess at theinternal shell of the sleeve and the internal shell of the sleeve isclosed in a pressure tight manner. Also in this clamping device theclamping areas can be disposed in an axially and/or radially distributedmanner to obtain an optimal clamping.

When the connection between the covering body and the sleeve is realizedin that these both elements can be rotated in relation to each otherduring the application of a pressure, it is advantageous to provide ananti-rotation-safety device between the sleeve and the covering body.

The proposed clamping devices can be a part of a height-adjustable seatpost which is marketable as a structural unit. A particular compactembodiment can be obtained when the tube of the seat post formssimultaneously the external shell of a gas pressure spring, i.e. whenthe gas pressure spring is integrated in the seat tube.

A gas pressure spring integrated into the seat tube wherein the tube ofthe seat post forms simultaneously the external shell of the gaspressure spring is considered separately as an invention.

An example of an embodiment of the invention is described in thefollowing by means of the drawings, wherein:

FIG. 1 a clamping device in the lateral view (cross-section B-B) and inthe top view (line A-A).

FIG. 2 a detail representation of the detail Z from the lateral viewB-B.

FIG. 3 an exploded drawing of the clamping device.

FIG. 4 a detail from the bicycle frame with a height-adjustable seatpost.

FIG. 5 a seat post with a clamping device with a high adjusted saddle.

FIG. 6 a seat post with a clamping device with a low adjusted saddle.

FIG. 7 a seat post with an alternative hydraulic clamping device.

FIG. 8 an exploded drawing of the alternative hydraulic clamping device.

FIG. 9 a three-dimensional schematic drawing of the alternativehydraulic clamping device.

FIG. 10 a seat post with a second alternative hydraulic clamping device.

FIG. 11 an exploded drawing of the second alternative hydraulic clampingdevice.

FIG. 12 a cross section drawing of the second alternative hydraulicclamping device.

The FIG. 1 shows a clamping device K in a lateral view (cross-sectionB-B) and in a top view (cross-section A-A). The device consists of anexternal tube as a covering body 1 in which a sleeve 2 is introduced,for example in the form of a shrink- or press-fit. The both tubes areinterconnected at the top and at the bottom at the positions 3 and 4.The connection can be a welding connection, a solder connection, asticking connection or a screw or any other connection who meets thepurpose. According to the realization of the media feed line describedbelow, the connection must be realized eventually media tight. Upperclamping tapering 7 (recesses) are introduced In the region B1 via thecircumference of the sleeve 2 and lower clamping tapering 6 areintroduced In the region B2 via the circumference of the sleeve 2. Theseclamping tapering 6, 7 are realized for example in milling the externalshell of the sleeve 2 and form the internal sides of the clamping areas6, 7.

The media feed line 5 is situated at the covering body 1. Via this mediafeed line a medium preferably incompressible like oil (hydraulic oil) isintroduced. In the internal shell of the covering shell 1 and/or in theexternal shell of the sleeve 2 are provided radial and axial media feedlines 8 and 9, wherein the medium can be transferred to the inner sideof the elastic clamping areas 6, 7. The media feed lines 8, 9 aremanufactured for example in milling grooves in the shell surfaces. Inother embodiments tube feed lines can be used, which can be introducedfor example in deeper millings or can be admitted from the exterior. Theradial, symmetrically chosen distribution in the example of realizationof the clamping areas 6, 7 can be clearly recognized in the crosssection A-A. If the symmetry of the clamping is not important, anotherdistribution, for example, a unilateral distribution of the clampingareas can be chosen.

FIG. 2 shows a magnified representation of the detail Z of the lateralview B-B. In this figure the radial media feed line 8 and the axialmedia feed line 9 can be clearly recognized. These media feed lines 8, 9connect all internal sides of the elastic clamping areas 6, 7.

In the exploded drawing according to FIG. 3, the construction of theclamping device is additionally made clearer in using identicalreference numbers.

When a medium, for example oil or another hydraulic liquid istransferred under pressure via the radial media feed line 5 and theradial and axial media feed lines 8, 9 on the internal side of theelastically clamping areas 6, 7, these surfaces are deformed elasticallyradial to the interior in the direction of the force arrows 10, 11, 12(FIG. 1) and fix a tube which is not represented in FIG. 2 and which isintroduced into the sleeve 2. The hydraulic system is evacuated beforeit is filled with the hydraulic liquid. Eventually an air vent screw orsimilar can be provided.

The constructive realization of the covering body 1 and of the sleeve 2,the radial and axial media feed lines 8, 9, of the lower and upperclamping taperings as well as there number and distribution on thecircumference may be realized by the person skilled in the art. Itdepends essentially on the dimensions and the desired clamping force.For a clamping device K for a seat post S the covering body has forexample a length of 85 mm and an external diameter of 31, 6 mm, adaptedto the seat tube SR, with a tube thickness of 1, 2 mm. The sleeve 2 hasthe same length and a tube thickness of 1 mm. The clamping taperings 6,7 have 120 mm² (square millimeter) and are tapering from the externalborder to the middle to a material thickness of approximately 0, 4 mm.The residual material thickness depends on the material itself as wellas on the available pressure and the necessary electrical deformation.

Embodiments for the cinematic inversion of the clamping device accordingto the invention can be realized by the person skilled in the art withinthe bounds of his skill.

FIG. 4 shows a detail of a bicycle frame with a high seat post S. Theclamping device K can be introduced into the seat tube SR. Within theseat post S is the gas pressure spring GF, which is supported on thelower end of the clamping device K. The clamping device K or only theexternal tube 1 or the sleeve 2 can be, according to the requirements,longer than it is shown in FIG. 1. A hydraulic line 13 is connected tothe radial media feed line 5, which hydraulic line is conducted alongthe upper tube OR of the bicycle frame to the handle bar L and ends at aremote control F. The fixing of clamping device K can be activated viathe operation of the lever of the lockable remote control, for example,according to the knee lever principle. If it is released, the seat postS can be pushed down by the weight of the driver and can be deployed byrelief during the ride, whereby the two hands of the driver can stay onthe handle bar. The constructive realization of a corresponding remotecontrol device depends on the skill of the person skilled in the art. Inthe construction of bicycles, especially for mountain bikes hydraulicsystems already exist, for example to actuate disk brakes. Instead ofthe gas pressure spring also a normal spiral spring etc. can be used.

FIG. 5 shows a detail of a bicycle frame with a seat post S in a highadjusted position. In opposition to the FIG. 4 no remote control deviceis shown, but the actuation of the clamping device K is realizeddirectly on this device itself by means of a turning knob D below thesaddle. FIG. 6 shows the same hydraulic seat post clamping as FIG. 5 ina low adjusted position.

The clamping device K according to the invention operates reliably anddue to the frictional connection has no play, so that on the one handcreak noises—even under dynamical load—are avoided and on the other handno wear and tear, depending on the clearance, exists. The radialclamping force operates uniformly on the seat post S and clamps it in anoptimal manner with high stiffness. In a non clamped state the seat postis guided approximately without clearance in the clamping zones, so thatthe seat tube can be moved easily. In the solution described in thistext a reasonable adjustment range of 180 mm (hundred and eighty) can berealized. Furthermore the gas pressure spring is arranged in a protectedmanner in the seat point. The clamping device can be manufactured in acompact and easy manner.

The FIGS. 7, 8 and 9 show an alternative hydraulic clamping device K forfastening a seat post S. Thereby are arranged on the circumference of asleeve 20 three piston devices 22, operating according to the principleof a disk brake found for example in bicycles. The piston devices 22 areinterconnected via common hydraulic lines 21, wherein the hydraulicfluid is introduced via the media feed line 5. The sleeve 20 is slidedfrom the exterior on the—here only shown—upper end of the seat tube SR(see also FIG. 4) and is fixed on this tube. The seat tube SR isprovided at the upper end distributed on its circumference with slots23. During pressure application the bolts are pressed on the externalshell of the seat tube SR whereby these bolts press the plates 25 of theseat tube SR in a force-fit manner on the seat post.

FIG. 9 shows a three-dimensional schematic drawing of the alternativehydraulic clamping device, whereby the right half is shown in crosssection and enables the view on the seat tube SR and the piston device22.

The FIG. 10 shows the schematic drawing of a seat post S with a secondalternative embodiment of the clamping device K, which is described inthe following more in detail by means of the FIGS. 11 and 12.

In the exploded drawing according to FIG. 11 are represented from thetop to the bottom: The lower end piece of a seat post to be clamped, asoil wipe off ring 19, a lock nut 18, an elastically deformable clampingsleeve 21, which can be made, for example, of plastics and whichcomprises a helicoidally circumferential channel 14 for receiving thepressure liquid and on the upper end thereof having provided a polygon20 as a part of a anti-rotation safety between the sleeve and thecovering body. The polygon 20 is realized in a conical manner and tapersfrom the top the bottom. At the lower end of the covering body 21 isprovided a circumferential cut-in groove 16′ for receiving the followingdescribed sealing washer 16.

The reference numbers 15 and 16 indicate an upper and a lower sealingwasher. The covering body 1 is found beneath. The sealing washers 15, 16which can be for example o-rings, are mounted in the zone of the upperand lower end of the clamping sleeve 21 and avoid the discharge of thehydraulic liquid between the covering body 1 and the sleeve 21.

A recess is found at the upper portion of the covering body, i.e. theinternal diameter is up to n the dashed—line 23 greater than in thePortion situated below. The sleeve 21 is adapted to the recess Thepolygon 20 of the clamping sleeve 21 founds a conical counter-fit at thetop of the covering body 1, so that the clamping sleeve 21 and thecovering body 1 cannot be furthermore twisted one to each other.

Below the reception 16′ for the washer, the covering body is provided atthe interior with two dashed indicated longitudinal grooves 17. Thesesgrooves receive the springs 22 of a socket B (which can be made ofplastics). The socket B itself is connected with the lower end of theseat post. For that purpose the seat post is inserted through thecovering body. The socket B operates then as an anti-rotation safety inthe released state, i.e. the pressure free state and simultaneously asan upper abutment safety, so that the seat post cannot leave theclamping device in the released state.

The connection between the seat tube S and the socket B is realized bymeans of a clamping screw KS. The latter comprises a thread 24, which isscrewed into a—for clearness reasons not represented—counter thread inthe internal tube of the seat post S. Thereby the groove 25 of thesocket engages with the recess 25′ of the seat tube, so that theanti-rotation connection of the socket B is realized with the seat tube.

FIG. 12 shows a three-dimensional schematic drawing of the secondalternative hydraulic clamping device, whereby the left half ispresented in a cross section. The same reference numbers are used forthe same elements. Especially the principle of the gas pressure springGF integrated into the seat post S can be recognized.

The clamping device unit with seat post represented in the FIG. 10 whichis structurally and independently sellable—with or without asaddle—comprises furthermore a nut M. The individual elevation height ofthe gas pressure spring GF can be adjusted.

1. Clamping device for a releasable force-fit fixing of a tubular objecthaving a sleeve, said device comprising at least one clamping areawhich, under pressure, is elastically deformable, the improvementwherein jointly supplied media feed lines are provided for each clampingarea, each clamping area being formed by a recess at the external shellof the sleeve, and wherein the external shell of the sleeve issurrounded pressure-tight by a covering body.
 2. Clamping deviceaccording to claim 1, wherein the clamping areas are disposed anddistributed on the sleeve at least one of axially and radially. 3.Clamping device according to claim 1, wherein the media feed lines areinserted in form of channels in at least one of the internal shell ofthe covering body and in the external shell of the sleeve.
 4. Clampingdevice according to claim 1, wherein the tubular object is a seat post.5. Clamping device for a releasable force-fit fixing of a seat post, theimprovement comprising at least one clamping area which is force-lockedwith a seat post upon application of hydraulic pressure.
 6. Clampingdevice according to claim 5, comprising a sleeve which receives the seatpost, comprising at least a one clamping area which, under pressure, iselastically deformable, wherein at least one media feed line is providedfor at least one clamping area, and wherein the external shell of thesleeve is surrounded pressure-tight by a covering body.
 7. Clampingdevice according to claim 5, wherein a spring force is applied to theseat post in an axial direction.
 8. Clamping device according to claim7, wherein the spring force is produced by a gas pressure spring. 9.Clamping device according to claim 8, wherein the device is applied tothe seat tube of a bicycle frame.
 10. Clamping device according to claim8, wherein the device forms a constructional unit with a seat tube of abicycle.
 11. Clamping device according to claim 10, further comprisingmeans for avoiding a rotation of the tubular object relative to the seatpost in the clamping device.
 12. Clamping device according to claim 6,wherein the elastically deformable clamping area is on the sleeveitself.
 13. Clamping device according to claim 6, wherein the media feedline includes a channel in the sleeve.
 14. Clamping device for areleasable force-fit fixing of an object having a sleeve, said devicecomprising at least one clamping area which, under pressure, iselastically deformable, the improvement wherein jointly supplied mediafeed lines are provided for each clamping area, each clamping area beingformed by a recess at the internal shell of the sleeve, and wherein theinternal shell of the sleeve is sealed in a pressure-tight manner. 15.Clamping device according to claim 14, wherein the clamping areas aredisposed and distributed at least one of axially and radially. 16.Clamping device according to to claim 1, further comprisinganti-rotation safety means disposed between the sleeve and the coveringbody.
 17. Height adjustable seat post having a clamping device accordingto claim
 1. 18. Height adjustable seat post according to claim 17,wherein a tube of the seat post forms the external shell of a gaspressure spring.
 19. Height adjustable seat post, wherein a tube of theseat post forms the external shell of a gas pressure spring. 20.Clamping device according to claim 12, wherein the sleeve is made of aplastic material.